Anyway, I've got a little problem with a brand new Oatley Electronics RIAA Stereo Preamp kit that I got yesterday. I got shipped the BRAND NEW revision...the K301. So there's not much out there about it. Nothing really.

It seems that I'm missing a pair of Zener diodes that are right in the main power path...ZD201 and ZD202. I'm wondering if any of you guys can help me identify them. They're in the bottom left area of the PCB and the top right of the schematic. Here's the PDF of the assembly instructions...

Boy, you said it. What a shame...two diodes. I'm sure I can find some goodies over there to tag along.

Hey, you read those instructions as taking AC straight in also right?
They shipped the kit with a wall wart that I don't think it needs anymore. They had an old revision that took those, but I'm 99% sure they don't anymore.

I'm pretty confused. I don't want to fry the thing , but the board says right on it 'AC IN'.

The notes also mention this...

"The incoming Mains AC supply is connected to the transformers primary. This can be configured for 100-120V or 200-240V AC operation."

But nowhere in there do they mention how to configure it for those loads.

For the zeners, they need not match provided their total voltage rating adds up to 30 volts. You could use 2x 12 volt and 1x 6 volt. (Mount one zener in the board as normal. In the other position, put one end of each remaining zener into a hole so that they stand up vertically from the board. Twist the free leads together. Solder them together and snip off excess length. Make sure they are all connected "nose to tail", or "anode to cathode".)

You won't need the "wall wart" if you are using the on-board transformer. Note that the transformer has two primary windings. The last picture in the PDF shows it wired for 200-240v operation.
(Mains in to pins A and D, pins B and C connected together, putting the windings in series.)

For 100/120v operation, the windings have to be connected in parallel.
Connect pin A to pin C.
Connect pin B to pin D.
Connect the mains to pins A and D.

If you are not using the onboard transformer and want to use a wall wart:
Remove the onboard transformer.
Connect a wall wart that outputs 12 volt AC (not DC) voltage, to the two empty holes left where you removed the onboard transformer.

I like what's Oatley is doing with these little amps, but it seems like they're kind of dropping the ball a bit. Between not sending me all the parts I need and not sending out proper instructions. Bit of a disappointment.

At any rate, thanks again! I will wire this for AC like you said. Any recommendations for a fuse rating? I found some 3amps in my parts bin.